This invention relates to a means for hydraulic self-leveling of a loader bucket and more particularly to a simplified means for maintaining a loader bucket in a level condition as the bucket is being raised or lowered by the tractor loader. Tractor loaders are in widespread use and generally comprise a pair of boom arms which are pivotally secured to a frame means mounted on the tractor. Many types of materials handling implements may be mounted on the boom arms with a common implement being a conventional loader bucket. The loader bucket is normally pivotally mounted on the forward ends of the boom arms and is pivotally movable with respect thereto by means of hydraulic cylinders. Ordinarily, upward movement of the boom arms causes the loader bucket to be rolled back or tipped back even though the bucket cylinders are not being actuated. Conversely, downward movement of the boom arms causes the loader bucket to tip forwardly towards a dumping position. In many operations, it is highly desirable to maintain the loader bucket in a level position while either raising or lowering the boom arms so that the material therein does not either fall rearwardly from the bucket as the bucket is being raised or fall from the forward end of the bucket as the bucket is being lowered.
Mechanical linkages have been provided for leveling the bucket during the movement of the boom arms but the mechanical linkages are quite costly, difficult to maintain, and add an objectionable large amount of weight to the overall assembly.
Therefore, it is a principal object of the invention to provide an improved and simplified means for automatic self-leveling of a loader bucket.
A atill further object of the invention is to provide a means for the hydraulic self-leveling of a loader bucket while the bucket is being raised or lowered.
A further object of the invention is to provide a means which automatically maintains the loader bucket in a level position while the boom arms are being raised or lowered without adding objectionable weight to the loader.
A further object of the invention is to provide a means for the hydraulic self-leveling of a loader bucket which may be mounted on existing loader devices.
A further object of the invention is to provide a means for hydraulic self-leveling of a loader bucket including a pressure relief valve means to prevent objectionable pressure build-up in the actuator cylinder.
A still further object of the invention is to provide a hydraulic cylinder having pressure relief valve means provided in the piston thereof to permit fluid flow from one cylinder compartment to the other upon a predetermined amount of fluid pressure being experienced in that compartment.
These and other objects will be apparent to those skilled in the art.